Cold Weather Fuel Requirements of Oldsmobile Diesels

Two Oldsmobiles with 5.7 L diesel engines and one with a 4.3 L diesel engine were tested to determine the effect of the low temperature properties of diesel fuel on operability (cold-start and warm-up driveability). Startability limits ranged from −18°C to −24°C and were unaffected by cetane quality of the fuel within the range of 39 to 50 cetane numbers. With untreated fuels, the cars would not operate when the fuel temperature fell below the cloud point of the fuel because wax crystals precipitated from the fuel and plugged the fuel tank filter. Low temperature operability was extended as much as 10°C by the use of fuel flow improver additives and a modified vehicle fuel system.